msem-instigator

Bloodprice {2}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Create X 2/2 black Demon creature tokens, where X is one plus the number of creatures that died this turn.

Destroy all creatures with mana value 3 or less.

Flying
Whenever Rivha and at least two other creatures attack, exile all other attacking creatures you control. For each creature exiled this way, create a 3/3 white Angel creature token with flying that's tapped and attacking.

First strike
Whenever a creature dealt damage by Roadside Reaper this turn dies, you may discard a card. If you do, put a +1/+1 counter on Roadside Reaper and draw a card.

Creatures you control get +2/+0 and gain menace until end of turn. (They can't be blocked except by two or more creatures.)

Whenever Roaring Illusion attacks alone, for each other creature you control, create a token that's a copy of that creature and that's tapped and attacking. Exile those tokens at the beginning of the next end step.

Search your library for up to two basic land cards and put them onto the battlefield tapped, then shuffle.
Fuse (You may cast one or both halves of this card from your hand.)

If a creature an opponent controls would die, exile it instead.
Whenever Rocket Poacher deals combat damage to a player, put a card exiled with it onto the battlefield under your control.

Trample
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Rockpounding Saurian enters, if tribute wasn't paid, you may destroy up to one target artifact, up to one target land and up to one target Fortress.

At the beginning of combat on each of your turns, you may sacrifice a land or exile a land card from your graveyard. If you do, create two 1/1 red Goblin creature tokens with haste. Exile those tokens at the beginning of the next end step.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its costs.)
{1}{R}, Discard a red card: Roggar deals 2 damage to any target. This damage can't be prevented.
{2}{R}, Exile a red card from your graveyard: Create two tapped 1/1 red Elemental creature tokens.

Choose three. You may choose the same mode more than once.
• Return target creature with mana value 2 or less to its owner's hand.
• Scry 1, then draw a card, then discard a card.
• Target creature gets -2/-0 until end of turn and attacks this turn if able.

Create a number of 3/3 green Elemental creature tokens equal to the number of differently named lands you control.
Fuse (You may cast one or both halves of this card from your hand.)

Target opponent looks at the top six cards of your library and separates them into a face-down pile and a face-up pile. Choose a pile, then play any number of cards from it without paying their mana costs. Put the rest of the cards into your graveyard.

Pay 3 life: Put a +1/+1 counter on target creature.

For each nontoken enchantment you control, conjure a duplicate of it into your hand. Until the end of your next turn, you have no maximum hand size.
Exile Root Duplication.

(Activate each submodule once as a sorcery. When this enters, activate one submodule for free.)
{G}{G}{G}: Seed
Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
{G}{G}{G}: Soil
Destroy target noncreature permanent.
{G}{G}{G}: Stem
Root Module gains “You may play an additional land on each of your turns.” and “Lands you control are every basic land type in addition to their other types.”

When Rootbound Awakener enters, create a green Aura enchantment token named Vivification attached to target creature or land. The token has enchant creature or land and “Enchanted permanent is a creature with base power and toughness 5/5 in addition to its other types.”

Defender
As long as you control an enchantment, Rooted Cavalier has vigilance and can attack as though it didn't have defender.

{6}: Create a 1/1 black Worm creature token.

Create a 1/1 green Saproling creature token for each nonland permanent card in your graveyard.

When Rotting Greatwurm dies, put three +1/+1 counters on target creature you control.
Fleeting {2}{G} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Destroy target land. Create a 2/2 black Zombie creature token.

Once each turn, when Rova, the Fleshweaver enters or you attack with one or more Horrors, you may put a +1/+1 counter on each creature you control. Then if Rova isn't a token, untap each land you control. Until your next turn, you may cast permanent spells as though they had flash.
{2}{G}{G}, Discard Rova: Create a token that's a copy of Rova, the Fleshweaver, except it's 4/4 and isn't legendary. Activate only as a sorcery.

When Roving Chaplains enters, create two 1/1 white Spirit creature tokens with flying.
{W}, Tap another untapped creature you control: Tap target nonland permanent an opponent controls.